CEPA Part III: nutrients

Part III of the Canadian Environmental Protection Act (CEPA) regulates the nutrient content of cleaning agents and water conditioners. When the Act was created, the Phosphorus Concentration Regulations, previously under the Canada Water Act, were incorporated under Part III. During the 1960s, one of the major concerns regarding the degradation of the Great Lakes focused on nutrient enrichment or eutrophication. Phosphorus was identified as the element responsible for eutrophication and, in 1972, controls were placed on the phosphorus content of household detergents. During the same period, programs were implemented at major municipal treatment plants in the Great Lakes Basin to control effluent phosphorus levels. During 1997, the House of Commons Standing Committee on Environment and Sustainable Development recommended that Environment Canada determine whether sources of nutrients are adequately regulated. As a consequence, the Federal Government initiated a major assessment of nutrients entering the Canadian environment through human activities to determine their impacts on aquatic and terrestrial environments.

The National Hydrology Research Institute (NHRI) has a continuing program to determine the relationships between the quantity of added nutrients and the response of bottom-dwelling biota, the cumulative effects of long-term nutrient loading, and the ecological consequences of interactions between nutrients and toxic substances. In 1997, two new research programs were initiated to:

• evaluate indices of primary productivity, nutrient status and taxonomic composition for assessing eutrophication of rivers in response to nutrient inputs; and
• evaluate the effects of nutrient loading from agricultural runoff on primary production in receiving waters.

The National Water Research Institute continued its assessment of changing nutrient discharges from sewage treatment plants in basins such as Hamilton Harbour and Severn Sound in Ontario. In addition, the NHRI examined the confounding effects of exotic species (like zebra mussels) and metals in Lake Erie and the Bay of Quinte, Lake Ontario.

The Wastewater Technology Centre is currently evaluating low-cost alternatives for enhancing nutrient removal from biological sewage treatment plants. The technologies currently being demonstrated include:

• the installation of biomass support media as a low cost alternative to upgrade for ammonia removal;
• a modification from continuous to intermittent aeration that will result in complete nitrogen removal as well as energy savings;
• the installation of simple secondary clarifiers to enhance plant capacity for nutrient removal; and
• the retrofit of a sewage treatment plant for complete biological nitrogen and phosphorous removal.